The present invention relates to an improved dresser for correcting a time-lapse change (due to a polishing operation) of a polishing surface of a polishing apparatus used to polish a surface of a work object to be polished, such as a semiconductor wafer, a method for manufacturing such a dresser, and a polishing apparatus and method utilizing such an improved dresser.
In a polishing apparatus used to polish a surface of an object (referred to as xe2x80x9cwork objectxe2x80x9d hereinafter) such as a semiconductor wafer, a polishing cloth which provides a polishing surface is adhered to an upper surface of a turntable, and, the work object mounted on a top ring is urged against the polishing surface, that is, an upper surface of the polishing cloth, and, the surface of the work object is polished by relative movement between the polishing surface and the work object while supplying an abrasive liquid (slurry) to the polishing surface of the polishing cloth.
In such a polishing apparatus, as the polishing operation is continued for a long time, abrasive particles of the abrasive liquid and polished waste matter from the work object adhere or stick in the polishing surface, with the result that the polishing surface of the polishing cloth changes over time. Thus, after the polishing operation is continued for a predetermined time period, the polishing surface of the polishing cloth must be dressed by using a dresser to effect surface correction and to correct the time-lapse change of the polishing surface. In the past, as such a dresser, a sintered ceramic dresser using a sintered ceramic material or an electrc plated dresser in which diamond particles are electro-deposited on a surface of the dresser has been used.
Regarding the above-mentioned conventional dressers, since the sintered ceramic dresser using the sintered ceramic material such as SiC, Si3N4 or Al2O3 is very fragile and brittle, it is difficult to manufacture the sintered ceramic dresser and the manufacturing cost thereof becomes expensive.
On the other hand, in the electro-plated dresser, as shown in FIG. 5, diamond particles are dispersed and electro-plated on a surface of a ring-shaped metallic substrate 100 by wet electro deposition so that, as shown in FIG. 6, the diamond particles 102 of several tens or hundreds of xcexcm are embedded into a plated layer 101.
In the electro plated dresser, the diamond particles sometimes drop from the plated layer during the dressing operation, with the result that the polished surface of the work object such as a semiconductor wafer is scratched by the diamond particles.
Particularly, in a dresser for dressing a polishing surface of a polishing apparatus used to polish a device pattern formed on the semiconductor wafer to flatten the latter, the diamond particles dropped during the dressing operation penetrate into the polishing surface, with the result that the polished surface of the semiconductor wafer becomes deeply scratched.
In view of the above-mentioned situations, the present invention has been made. An object of the present invention is to provide an improved dresser for a polishing surface, which can eliminate the above-mentioned conventional drawbacks and can be easily manufactured and in which a polished surface of a work object such as a semiconductor wafer is not scratched, a method for manufacturing such a dresser, and a polishing apparatus utilizing such an improved dresser.
To achieve the above object, according to one aspect of the present invention, there is provided a dresser for dressing a polishing cloth such as non-woven fabric to effect surface correction and to correct changes by dressing a polishing surface of a polishing cloth (non-woven fabric) of a polishing apparatus, wherein a number of spired projections are formed on a surface of a metallic substrate and at least a portion of the surface of the metallic substrate on which the projections are formed is covered by a wear-resistant hard film.
According to another aspect of the present invention, the dresser for the polishing surface may be constituted so that (a) the wear-resistant hard film is formed from one of a transition metal group nitride film, a nitride group ceramic film, a carbide group ceramic film, an oxide group ceramic film, a diamond-like carbon film, a composite ceramic film, a nitride film and a carbide film, and (b) the transition metal group nitride film or the nitride film is made of titanium nitride.
The present invention further provides a polishing apparatus comprising a polishing cloth adhered to an upper surface of a turntable, a top ring capable of urging an object to be polished (work object) against a polishing surface of the polishing cloth, an abrasive liquid supplying nozzle for supplying abrasive liquid to the polishing surface, and an improved dresser. The polishing apparatus according to the present invention includes a dressing mechanism for dressing the polishing surface of the polishing cloth. The dressing mechanism includes a dressing member capable of urging a surface of the dresser against the polishing surface and a water supplying nozzle capable of supplying water to the polishing surface. The surface of the dresser is obtained by covering a surface of a metallic substrate on which a number of projections are formed by a wear-resistant hard film. The wear-resistant hard film is formed from one of a transition metal group nitride film, a nitride group ceramic film, a carbide group ceramic film, an oxide group ceramic film, a diamond-like carbon film, a composite ceramic film, a nitride film and a carbide film; and the transition metal group nitride film or the nitride film is made of titanium nitride.
The present invention further provides a method for manufacturing a dresser for dressing a polishing surface to effect surface correction and to correct time-lapse change of the cloth by dressing a polishing surface of the polishing cloth of a polishing apparatus, in which, after a number of spired projections are formed on a surface of a metallic substrate by a machining technique, a wear-resistant hard film is formed on at least a portion of the surface of the metallic substrate on which the projections are formed.
The method for manufacturing the dresser for the polishing surface according to the present invention may be designed so that (c) the wear-resistant hard film is formed from a ceramic film and the ceramic film is formed by chemical deposition, physical deposition, spraying, wet plating or melting plating, (d) the physical deposition is effected by a film-forming method utilizing spattering, ion plating, ion injection or ion beam, (e) the wear-resistant hard film is formed from a titanium nitride film and the titanium nitride film is formed by chemical deposition, physical deposition, spraying or wet plating, (f) the wear-resistant hard film is formed from a titanium nitride film and the titanium nitride film is formed by a dynamic mixing method in which titanium (as transition metal) is vacuum-deposited and at the same time ion beams (mainly including nitrogen ions) are irradiated, (g) the wear-resistant hard film is formed from a diamond-like carbon film and the diamond-like carbon film is formed by chemical deposition, physical deposition, spraying, wet plating or melting plating, or (h) the wear-resistant hard film is formed from a diamond-like carbon film and the diamond-like carbon film is formed by a dynamic mixing method in which carbon is deposited and at the same time ion beams (mainly including nitrogen ions) are irradiated.